Carlos M G Duran

University of Montana, Missoula, Montana, United States

Are you Carlos M G Duran?

Claim your profile

Publications (54)123.69 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Selection of the best tissue valve is an essential step before percutaneous aortic valve replacement (PAVR) becomes a clinical reality. The aim of this study was to evaluate in vitro three different tissue valves mounted within the same endovascular stent. Thirty stented valves (10 aortic porcine, 10 pulmonary porcine, and 10 pericardial tubular) were sutured within a 32-mm long by 23-mm diameter cobalt-nickel stent. The porcine valves were trimmed down close to the cusps. All valves were delivered with a percutaneous valvuloplasty catheter and placed orthotopically in a latex root that was cast from a sheep's aorta. The roots were tested in a pulse duplicator at a rate of 60 beats per minute and 3.5 liters per minute. The transvalvular gradient, maximum valve orifice area, and presence of central and paravalvular leaks were recorded echocardiographically. Within the limitations of implantation in a synthetic, noncalcified annulus, the pericardial valve performed best in terms of orifice area, transvalvular gradients, and tissue bulk; but four of the ten valves showed a central leak due to the type of stent used. The ideal valve for PAVR should collapse with minimal bulk to avoid coronary obstruction and central and paravalvular leaks. The tubular pericardial valve showed the lowest pressure gradients and was the most compressible, but was more open to manufacturing errors.
    Journal of Cardiac Surgery 04/2008; 23(3):234-8. · 1.35 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Recent awareness of the importance of the mitral valve's basal chordae stimulated a comparative anatomic study of these chordae in 11 human, 10 ovine, and 10 porcine hearts. The basal chordae were defined as the chordae that arise from the papillary muscles and insert into the ventricular aspect of the leaflets. All leaflet insertions of the basal chordae were close to the annulus, except at the anterior mitral leaflet, where insertion was at the junction of the smooth and rough zones. The number of basal chordae was 24.6 +/- 4.21 in the porcine, 19.7 +/- 2.90 in ovine, and 18.81 +/- 3.54 in the human hearts. At least two anterior basal chordae were present in each half of the anterior leaflet in 70% of ovine and porcine and in 100% of human hearts. At least two basal chordae were present in each half of the middle scallop of the posterior mitral leaflet in 80% of ovine, 70% of porcine, and 63.6% of humans. Among them, only the two principal or strut chordae were identified as the longest and thickest. The basal chordae of the mitral valve follow a definite pattern in each of the three species studied. A new and logical terminology that should facilitate identification of specific basal chordae is suggested.
    The Annals of thoracic surgery 11/2007; 84(4):1250-5. · 3.45 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In a previous sono-metric study, changes were described that occurred in the normal tricuspid valve during the cardiac cycle. However, the wealth of data available suggested the need for reporting further findings that should contribute to a better understanding of the dynamics of the tricuspid valve. Thirteen sonomicrometry transducers were placed in the hearts of each of seven sheep. Six transducers were placed in the tricuspid annulus (TA), at the base of each leaflet, and at each commissure; three at the tips of the papillary muscles (PMs); three in the free edges of the leaflets; and one transducer was placed at the apex. Distances between transducers, pulmonary and right ventricular pressures, and pulmonary flow were recorded simultaneously. The TA area underwent two major contractions and expansions during the cardiac cycle, reaching its maximum during isovolumic relaxation and its minimum in diastole. The TA height-to-width ratio changed from 8.4 +/- 1.9% to 15.3 +/- 4.2%. The leaflets began to open before end-systole. By the end of isovolumic relaxation, the leaflets had completed 54.1 +/- 13.4% of their opening. The PM and TA planes were not parallel, but were offset by 11.5 +/- 1.9 degrees to 17.8 +/- 2.1 degrees. The PM rotated 6.9 +/- 0.9 degrees with respect to the TA, with 3.1 +/- 1.1 degrees of the rotation occurring during ejection. The tricuspid valve is not a passive structure but rather forms a dynamic part of the right ventricle. Its orifice area changes not only due to the contraction and expansion of its perimeter but also to changes in its saddle shape. Leaflet opening and closure is not simply a response to pressure. The PMs rotate in relation to the TA. These data should impact upon the diagnosis and surgery of functional tricuspid regurgitation.
    The Journal of heart valve disease 10/2007; 16(5):511-8. · 1.07 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Coronary flow obstruction is a serious complication reported in percutaneous aortic valve replacement. In an in vitro study of porcine hearts, the effects of valved stent implantation on coronary artery flow were studied with the native valve's leaflets intact and excised. The right and left main coronary arteries of porcine hearts were dissected 20mm distal to the aortic root and directed into lengths of latex tubing leading to collection flasks. The ascending aorta was cut proximal to the brachiocephalic trunk, cannulated, and attached to a constant-head water supply. After steady flow was achieved, the flow rate from each coronary artery was measured. In Group A (n=10), a tubular pericardial valve sutured into a cylindrical, cobalt-nickel stent was deployed orthotopically using a valvuloplasty balloon catheter. In Group B (n=10), the native leaflets were removed before similar valve deployment. Coronary flow measurements were repeated post-implantation. In Group A, valve implantation resulted in a significant decrease in both left and right coronary flows. In Group B, no significant change in either right or left coronary flow was found after valve placement. Implantation of a percutaneous valved stent in the orthotopic position with the native valve in place causes coronary ostial obstruction. This problem highlights the need for modified stents that are designed for implantation in patients with non-retracted, fibrotic, or calcified leaflets.
    European Journal of Cardio-Thoracic Surgery 09/2007; 32(2):291-4; discussion 295. · 2.67 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Although it is known that the papillary muscles ensure the continuity between the left ventricle (LV) and the mitral apparatus, their precise mechanism needs further study. We hypothesize that the papillary muscles function as shock absorbers to maintain a constant distance between their tips and the mitral annulus during the entire cardiac cycle. Sonomicrometry crystals were implanted in five sheep in the mitral annulus at the trigones (T1 and T2), mid anterior annulus (AA) mid posterior annulus (PA), base of the posterior lateral scallops (P1 and P2), tips of papillary muscles (M1 and M2), and LV apex. LV and aortic pressures were simultaneously recorded and used to define the different phases of the cardiac cycle. No significant distance changes were found during the cardiac cycle between each papillary muscle tip and their corresponding mitral hemi-annulus: M1-T1, (3.5+/-2%); M1-P1 (5+/-2%); M1-PA (5+/-3%); M2-T2 (2.7+/-2%); M2-P2 (6.1+/-3%); and M2-AA (4.2+/-3%); (p>0.05, ANOVA). Significant changes were observed in distances between each papillary muscle tip and the contralateral hemi-mitral annulus: M1-T2 (1.7+/-3%); M1-P2 (23+/-6%); M1-AA (6+/-3%); M2-T1 (8+/-3%); M2-P1 (10.5+/-6%); and M2-PA (12.6+/-8%); (p<0.05 ANOVA). The distance changes between LV apex and each papillary muscle tip were significantly different: apex-M1 (12.9+/-1%) and apex-M2 (10.5+/-1%) and different from the averaged distance change between the LV apex and each annulus crystal (8.3+/-1%) with p<0.05. The papillary muscles seem to be independent mechanisms designed to work as shock absorbers to maintain the basic mitral valve geometry constant during the cardiac cycle.
    European Journal of Cardio-Thoracic Surgery 07/2007; 32(1):96-101. · 2.67 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Percutaneous aortic valve replacement has been performed in humans mainly for non-surgical candidates. We evaluated on animals a transapical approach to deliver an aortic stented valve without cardiopulmonary bypass. A tubular pericardial valve fixed within a cobalt-nickel stent (Medtronic, Inc.) was implanted using a transapical approach in five adult sheep. A left thoracotomy was used to access the apex of the heart. The crimped valve was deployed in orthotopic position with a valvuloplasty balloon catheter on the beating heart after decreasing the left ventricular pressure by using either drugs or inferior vena cava occlusion. Deployments were performed under fluoroscopy and epicardial 2D Doppler echocardiography. Exact positioning of the valve into the target area was confirmed by autopsy at the end of the procedures. Valves were unsuccessfully deployed at the target site in all cases but one. Three valves were implanted in a supra-annular position with two of them in supracoronary position. One valve was implanted below the native annulus in the outflow tract. Valvular leak was noted in all but one implants. Coronary obstruction occurred twice and early valve retrograde migration once. Ventricular fibrillation or diastolic cardiac arrest occurred less than 20 minutes after stent deployment in all cases. In our experience the transapical approach does not facilitate delivery of a stented valve. Despite its technically feasibility, advanced stent design and improvements in delivery system are required before to continue experimental studies in transapical approach for aortic stented valve.
    Annales de Cardiologie et d Angéiologie 07/2007; 56(3):122-5. · 0.30 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND AND AIM of the study: One objective of mitral valve repair is to restore the distorted mitral apparatus geometry to its normal dimensions specific for each patient. Because all dimensions of the normal aortic and mitral valves should be related, it was hypothesized that, in the presence of a normal aortic annulus, it would be possible to determine the dimensions of the structures needed for mitral valve repair. In seven sheep, sonometric ultrasound crystals were implanted at the left and right trigones (T1, T2), lateral annulus (P1, P2), and the tips of the anterior and posterior papillary muscles (Ml, M2). The distances T1-T2, M1-M2, T1-M1, T2-M2, P1-P2, P1-M1, and P2-M2 were measured at end-systole (ES), end-diastole (ED), and maximum and minimum lengths. Using these measured distances, fractional relationships were computed, and the average fractional relationship was used to determine a 'calculated' distance. The 'measured' and 'calculated' distances were then compared using a paired t-test. All fractional relationships were close to 1, with ED 1.00 +/- 0.21, ES 0.99 +/- 0.19, maximum length 0.99 +/- 0.19, and minimum length 0.94 +/- 0.21. The intertrigonal distance (T1-T2) expanded by 4.19 +/- 3.81%, and the transverse diameter (P1-P2) contracted by -6.15 +/- 3.69% from ED to ES. The interpapillary muscle distance (M1-M2) contracted -22.3 +/- 6.5%. The two distances with the least amount of contraction were those of T1-M1 and T2-M2, with contractions of -3.06 +/- 2.39% and -3.27 +/- 1.37%, respectively. P1-M1 and P2-M2 expanded 5.60 +/- 2.89% and 6.84 +/- 3.60% from ED to ES. The mitral valve dimensions and calculated fractional relationships were similar in all sheep. As shown previously, the ratio of aortic annulus diameter (easily measured echocardiographically) to the intertrigonal distance (T1-T2) is 0.79 and 0.80 in humans and sheep, respectively. This distance can be used to determine normal mitral valve geometry and, therefore, preoperatively to calculate the degree of geometric distortion present in individual patients.
    The Journal of heart valve disease 06/2007; 16(3):260-6. · 1.07 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objective Percutaneous aortic valve replacement has been performed in humans mainly for non-surgical candidates. We evaluated on animals a transapical approach to deliver an aortic stented valve without cardiopulmonary bypass.
    Annales De Cardiologie Et D Angeiologie - ANN CARDIOL ANGEIOL. 01/2007; 56(3):122-125.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Percutaneous aortic valve replacement has been proposed as a valid alternative to surgery in selected cases; however, it still has many problems. As a less radical preliminary step, we implanted a balloon-expandable stented aortic valve under direct vision in sheep. Under cardiopulmonary bypass (CPB) and through a transverse aortotomy, an aortic valve mounted in a long tubular balloon-expandable stent was implanted in six acute sheep. The leaflets were not excised and no anchoring sutures were used between stent and native annulus. Epicardial, two-dimensional color Doppler echocardiography was used to assess the function of the stented valve followed by macroscopic inspection at necropsy. Direct visualization of the entire annulus when the collapsed, valved stent was placed within the aortic root was difficult in all animals. Valve deployment took less than 1 minute. The surgical procedure resulted in major complications in all cases. Migration (3/6), paravalvular leak (2/6), mitral conflicts resulting in mitral regurgitation (1/6), and coronary ostia obstruction (2/6) were the major events at the origin of the failure. Only three animals could be weaned from CPB but did not recover enough to survive the procedure. Sutureless implantation of a stented aortic valve through standard CPB and aortotomy is far more complex than expected. Changes in stent design and surgical approach are indicated.
    Journal of Cardiac Surgery 12/2006; 22(1):13-7. · 1.35 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The surgical method of ventricular reconstruction described by Dor is recalled with the clinical report of a patient who presented a ventricular aneurysm. The left ventricular reconstructive surgery is based on an anatomical design of the heart described by Torrent-Guasp, where the normal orientation of the left ventricular muscle fibers, oblique in direction, is found parallel with the base of the heart at the time of ventricular dilation. By giving again an elliptic form to the left ventricle, the left ventricular reconstructive surgery improves the cardiac function of the patient who developed a bulky aneurysm after an infarction. Based on this concept, other techniques of ventricular reconstruction intended for patients presenting dilated cardiomyopathy, of ischemic origin or not, are being studied.
    Annales de Cardiologie et d Angéiologie 11/2006; 55(5):260-3. · 0.30 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Systolic descent of the atrioventricular plane toward the relatively stationary left ventricular apex is well described. As the atrioventricular plane includes two separate valvular units, systolic atrioventricular plane displacement should not be homogenous. In 6 sheep, sonomicrometric crystals were implanted at the base of the right coronary sinus, anterolateral and posteromedial fibrous trigones, posterior mitral annulus, left ventricular apex, and the tips of the anterior and posterior mitral leaflets. The aortomitral angle was calculated and related to simultaneous left ventricular and aortic pressures and mitral valve movement. The aortomitral angle was largest at end diastole (150.73 degrees +/- 15.48 degrees ). During isovolumic contraction, it narrowed rapidly to 144.90 degrees +/- 16.64 degrees , followed by a slower narrowing during ejection until it reached its smallest angle at end systole (139.66 degrees +/- 16.78 degrees ). During isovolumic relaxation, the aortomitral angle increased to 143.66 degrees +/- 16.02 degrees at the beginning of diastole. During the first third of diastole, it narrowed again to 141 degrees +/- 16.24 degrees before re-expanding to maximum at end diastole. During systole, the atrioventricular plane descended non-homogeneously toward the apex, with kinking at the hinge between the aortic and mitral annulus plane. This deformation of the atrioventricular plane has relevance in valve surgery.
    Asian cardiovascular & thoracic annals 11/2006; 14(5):394-8.
  • Source
    E Flecher, S Wilson, C M G Duran
    Heart (British Cardiac Society) 11/2006; 92(10):1495. · 5.01 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Durability remains the main problem of all bioprosthetic valves, and calcification is the major cause of failure. New tissue treatment processes are expected to reduce mineralization. A comparative animal study was undertaken to evaluate the behavior of a new-generation porcine bioprosthesis in contrast with a first-generation porcine bioprosthesis. The primary goal was to evaluate the efficacy of alpha-amino-oleic acid as an anticalcification treatment. Seventeen Targhee sheep (aged 4.5-7 months) had a mitral valve replacement with a Mosaic or Hancock Standard. The animals were followed up to 20 weeks (144.1 +/- 4.0 days vs 144.3 +/- 8.2 days) and then euthanized as scheduled. After gross examination, the explants were radiographed for the presence of calcification. The central portions were preserved for histologic examination, and the remainder of the sample was analyzed for quantitative calcium content by atomic absorption spectroscopy. Four Mosaic sheep were excluded because of perioperative surgical mortality. The remaining 13 were enrolled in the study (9 Mosaic and 4 Hancock Standard). The mean calcium content was 1.97 +/- 2.21 microg/mg tissue weight for Mosaic versus 8.36 +/- 4.12 microg/mg for Hancock Standard valves (P < .01). Mild fibrous tissue overgrowth and fibrinous lining were observed regardless the xenograft type. The low level of calcification in the Mosaic versus Hancock Standard xenografts confirms the efficacy of alpha-amino-oleic acid treatment in mitigating mineralization. A longer durability is expected with the clinical use of the Mosaic porcine valve.
    The Journal of thoracic and cardiovascular surgery 11/2006; 132(5):1137-43. · 3.41 Impact Factor
  • Jorge Solís, Stephen P Hiro, Carlos M G Durán
    Revista Espa de Cardiologia 10/2006; 59(9):985. · 3.20 Impact Factor
  • Source
    Carlos M G Duran
    The Journal of heart valve disease 08/2006; 15(4):521-3. · 1.07 Impact Factor
  • E M Flecher, T M Joudinaud, C M G Duran
    [Show abstract] [Hide abstract]
    ABSTRACT: Surgery is no longer the only technique to replace a cardiac valve. New percutaneous procedures allow aortic or pulmonary valve implantation. Even if the feasibility of these procedures has been proved, cases reported are very rare and selected. This emergent technology is still at an early stage of development and new prospective studies will be necessary to evaluate these procedures correctly before concluding their clinical benefit. At this time surgery remains the gold standard in terms of cardiac valve replacement.
    Annales de Cardiologie et d Angéiologie 07/2006; 55(3):144-8. · 0.30 Impact Factor
  • Source
    Thomas M Joudinaud, Erwan M Flecher, Carlos M G Duran
    [Show abstract] [Hide abstract]
    ABSTRACT: Advances in echocardiography have awoken new interest in the tricuspid valve, which otherwise has been largely ignored by cardiologists and surgeons. These advances demand a precise terminology for the description of the tricuspid valve's different anatomic structures in health and disease. While simple nomenclatures have been developed for the mitral valve, no such system has been described for the tricuspid valve. In order to develop a tricuspid valve terminology similar to the existing mitral valve nomenclature, a study of 50 porcine hearts was conducted. The study was designed not as a strict anatomical description but rather as a search for common parameters between both valves. The findings were based on the traditional understanding that the tricuspid valve has three main leaflets and three papillary muscles. The leaflets were defined according to their heights (free edge to base) and their chordal insertions. The papillary muscles were grouped according to the distribution of their chords to a commissure and its contiguous main leaflets. In all hearts, three main leaflets were found: septal (S), anterior (A), and posterior (P), associated with a variable number of commissural leaflets (C). Three groups of papillary muscles could be identified: anteroseptal with a mean of 1.78 muscles (range: 1-4), anteroposterior with 1.08 muscles (range: 1-4), and posteroseptal with 2.42 muscles (range: 1-5). Each group was identified (counterclockwise) with the numerals 1 (anteroseptal), 2 (posteroseptal), and 3 (anteroposterior). Each half of the leaflets and their corresponding commissures were identified by the initial letter of their classic name (S, A, P, or C) and their supporting papillary muscle group (1, 2, or 3). This system provides a method for reporting echocardiographic and surgical findings for the tricuspid valve. The system parallels previously described mitral valve nomenclature. This unified terminology should facilitate the precise recording of echocardiographic and surgical data.
    The Journal of heart valve disease 06/2006; 15(3):382-8. · 1.07 Impact Factor
  • E. M. Flecher, T. M Joudinaud, C. M. G. Duran
    [Show abstract] [Hide abstract]
    ABSTRACT: Surgery is no longer the only technique to replace a cardiac valve. New percutaneous procedures allow aortic or pulmonary valve implantation. Even if the feasibility of these procedures has been proved, cases reported are very rare and selected. This emergent technology is still at an early stage of development and new prospective studies will be necessary to evaluate these procedures correctly before concluding their clinical benefit. At this time surgery remains the gold standard in terms of cardiac valve replacement.
    Annales de Cardiologie et d Angéiologie 06/2006; 55(3):144-148. · 0.30 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The surgical method of ventricular reconstruction described by Dor is recalled with the clinical report of a patient who presented a ventricular aneurysm. The left ventricular reconstructive surgery is based on an anatomical design of the heart described by Torrent-Guasp, where the normal orientation of the left ventricular muscle fibers, oblique in direction, is found parallel with the base of the heart at the time of ventricular dilation. By giving again an elliptic form to the left ventricle, the left ventricular reconstructive surgery improves the cardiac function of the patient who developed a bulky aneurysm after an infarction. Based on this concept, other techniques of ventricular reconstruction intended for patients presenting dilated cardiomyopathy, of ischemic origin or not, are being studied.
    Annales De Cardiologie Et D Angeiologie - ANN CARDIOL ANGEIOL. 01/2006; 55(5):260-263.
  • Jorge Solís, Stephen P. Hiro, Carlos M. G. Durán
    Revista Espanola De Cardiologia - REV ESPAN CARDIOL. 01/2006; 59(9):985-985.

Publication Stats

720 Citations
123.69 Total Impact Points

Institutions

  • 2002–2008
    • University of Montana
      • The International Heart Institute of Montana Foundation at Saint Patrick Hospital and Health Sciences Center
      Missoula, Montana, United States
    • Hôpitaux Universitaires La Pitié salpêtrière - Charles Foix
      Lutetia Parisorum, Île-de-France, France
  • 2004–2005
    • Nanyang Technological University
      • School of Mechanical and Aerospace Engineering (MAE)
      Singapore, Singapore
  • 2003
    • Universität Regensburg
      • Lehrstuhl für Herz-, Thorax- und herznahe Gefäßchirurgie
      Regensburg, Bavaria, Germany
    • National University of Singapore
      Tumasik, Singapore